Category: ICON

It seems to me to be a tale of two lows, tonight’s rather interestingly, some may say bizarrely, hasn’t attracted any warnings for heavy rain so far from the Met Office (fig 1), but they have already issued an early warning for the possibilities of heavy rain for the low that will affect southeast England later on Sunday. Depending on what NWP model you look at the accumulations for Friday don’t look particularly that heavy (fig 2), but I wouldn’t have thought it would have hurt to have issued a blanket yellow warning for southern and central areas for 15 to 25 mm locally 40 mm, but what do I know. I suppose they still have time to do it but it’s cutting it a bit fine.

A lovely solar halo this morning here in mid-Devon which is the old weather lore precursor for rain in 6 to 9 hours, so I’m curious about just how fast the rain will spread across the southwest of England this afternoon, so here are the latest forecasts as of 09 UTC this Easter Sunday morning as a reminder.

Figure 1 – Courtesy of www.wxcharts.eu, BBC and the Met Office

Well all the models were much too slow in bringing the rain northeast across the southwest peninsula, and the BBC and Met Office forecasts weren’t much better either. If you look at the 15 UTC weather radar the rain had extended as far as Somerset (fig 2), nothing spectacularly wrong perhaps, only out by a couple of hours or so, but the various forecasts that I took a snapshot of (fig 1) were only for six hours ahead and should have been spot on. At least the old weather saying about solar halos still works!

Not a lot going on at the moment weather wise across the British Isles, but hopefully it should brighten up in many places today from the west on the passage of this frontal system (fig 1). I did notice that there’s been another minor SSW event that looks to have occurred just before the equinox (fig 2).

Figure 2 – Courtesy of the CPD at the JMA

That, along with some wild NWP output, is what probably led to all those stories of a snowy Easter, stories which now seem to have been summarily dropped like a hot potato. Having said that the models do take each successive Atlantic low a little further south into Biscay as the week progresses leaving the country in an easterly, anticyclonic in the north and cyclonic in the south, so it look’s odds on that’ll it will be a cold Easter (fig 3).

I wonder what the collective noun is for a number of NWP models? You know the kind of thing – a murder of crows, a murmuration of starlings, an exaltation of larks. Perhaps its simply a pile of crap? That may sound a bit harsh, but that’s the thought that ran through my mind when I compare short-range model output in this current spell of severe weather across the country.

All I really want to know is how long is it going to snow, and although they all provide you with some kind of solution, they are all quite different and not that convincing. In the early 21st century you might have least expected some commonality between them at the T+18 or T+24 range, but no that doesn’t seem to be the case, well at least not with the forecast for midnight tonight. Perhaps I am just too naïve to have thought they would have been, probably because I watch too much Star Trek. Perhaps it’s the ongoing SSW event that’s sending the models a little crazy at the moment, I would be fascinated to see just how the UKMO model is coping with the current situation, hopefully it’s better than this lot:-

I’m getting confused about the latest developments to the southwest of the UK. As you can see in the visible satellite image animation (fig 1) a cap of cloud has developed at around 49° north and 12° west and is spinning towards Cornwall. I’m trying to reconcile this with the T+03 from the ICON model (fig 2). The cap of cloud may indeed be this feature (the one that I thinks mis-labeled H 986 hPa). If it is, I think the cloud might be 2° further north, and If I’m right, the ICON model does seem to be a long way out already to say it was only run three hours ago!

Figure 2 – Courtesy of wxcharts.eu

Here’s the 14 UTC plotted chart (fig 3), as you can see there are few ships or weather buoys and just about anything could be lurking to the northwest of La Coruña.

Figure 3

If you know what’s happening then please do feel free to drop me a line.